This invention relates to drum support apparatus and more particularly to supports for photosensitive drums that prevent drum run-out. In present reproduction machines, a problem has been encountered with photoreceptor drum radial run-out of up to 0.050 inches or more. The reason for such a deviation in tolerance lies with the drums and how they are handled in manufacturing and in the field. Hitting the rim of the drum deforms the counterbore, and an out-of-tolerance condition occurs when endbells bells that interference fit with the drum are reassembled in the drum. This is especially true of the inner endbell in and a number of reproduction machines which is concave by about 5 inches. A slight cock in its assembly throws its shaft support bearing off center considerably due to magnification of the error by the length of the concavity. Since in a number of reproduction machines the shaft that is journaled to the machine frame is cantilevered from the frame to support a photoconductor drum without an exterior support, more run-out is observed with the inboard side of the photoconductor drum than on the outboard side.
In some reproduction machines that employ photoconductor drums that have endbells bells secured thereto by means of a series of tie rods, a problem has been encountered with localized distribution of forces, i.e., the force exerted by the tie rods is directed primarily at the area in which the tie rod is located as opposed to a uniform distribution of force throughout the end bells.
A solution of the above-mentioned problem of drum radial run-out is required before improved reproduction machines can be marketed incorporating magnetic brush rolls in the development process instead of cascade development because reducing the radial drum run-out minimizes the effects of the drum tolerance on spacing between the drum and the magnetic rollers.
Accordingly, it is an object of the present invention to provide a drum support apparatus that substantially reduces drum run-out.
Another object of this invention is to minimize the effects of drum tolerances on the spacing between a drum and a magnetic brush.
The foregoing and other objects of the present invention are accomplished by including a recess on the connecting surface of a hub that mates with a tab located on a member fitted on a support shaft whereby twisting of the hub creates a semi-rigid body that is subsequently tightened by a nut secured to the shaft.